I don't think any of them are doing the right thing. They're all doing things wrong and that might be a part of what makes this story line so irresistible. I don't think it's not that she doesn't love him, but you are right, cheating is nasty and flip flopping like that makes her come off as desperate. Which... I guess she is. xD
I agree with Crunchytunaroll. Though I will say, she probably would have stayed faithful if her husband had he paid more attention to her. I feel like the only reason she did it was because she's extremely horny and was looking for an outlet which her husband was not (at the time) providing. Now I'm not saying what she did was right by any means, just that there was reason behind her madness.
It'll be interesting to see if he will be able to kill her when he finds out (that seems to be part of his job, killing cheaters I mean...)
Instead of that, what gets to me is how she now knows her husband is willing to spend more time with her and satisfy her needs, but she still uses the chicken boy for sex. Even though her husband trusts her completely. At the beginning it was understandable but now there's just no reason to cheat. (Not that you should treat on your partner anyway)
She admitted to herself that she wants both of them not just one. It was her inner thoughts but still.
CheshireCat, I don't think that Ha Jin trusts anyone completely. The dude is mentally ill. He just doesn't think highly enough of her to keep tabs on her immediately, he even put cameras in his own house to keep an eye on her! Who does that? I think that what she's doing is definitely the least flattering outlet to her issues, I think that we tend to justify his psychopathic tendencies just because everyone hates being cheated on. I'm not gonna lie, I'm rooting for the wife to get her stuff together and show her husband that she is a force to be reckoned with. And maybe pick up the pink haired girl and break her in half... I still can't believe I'm reading this story line. T_T

Am I the only one who really hates the wife? Her using the chicken boy for sex and then telling her husband how much she "loves" him is just nasty ┑( ̄Д  ̄)┍